Term used when climbing (indoors or outdoors) and having enough lower body weight, especially in the posterior, to make it difficult to go up and over outcroppings of (sometimes fake) rock. It is especially used among women who have a lower center of gravity and additional layers of fat (especially in the butt region) than men.

Used in phrases such as "Damn, my ass gravity will not let me up and over this overhang!". Or, "I'm really tired and my ass gravity is not helping".